Allergen detector system and method

Abstract

An allergen particle detecting apparatus has a passageway through which environmental air is directed. A light beam is directed across the passageway so that portions of the beam will be scattered if any particles are present in the path of the beam. A beam blocking device on the opposite side of the passageway blocks any non-scattered portion of the beam while transmitting any scattered portions of the beam along a light path in the apparatus. Any light scattered by allergen size particles will be traveling in a predetermined angular range, and a pinhole device is positioned in the light path so as to transmit only light traveling in that angular range. Light transmitted through the pinhole device is detected by a light detector and an alarm output signal is produced if the detected amount of light is above a predetermined level.

We claim: 
     
       1. An allergen detecting apparatus for detecting the presence of allergen particles in environmental air, comprising: an outer housing having a passageway for air flow through the housing;   a light source on one side of the passageway for directing a light beam through the air passing through the passageway;   a beam blocking device on the other side of the passageway facing the light source for blocking any portion of the light beam transmitted directly across the passageway without scattering and transmitting any portion of the light beam scattered by impact with particles in the light path;   a light passageway in the housing extending from the beam blocking device for directing light transmitted through the beam blocking device along a light path;   a discriminating device positioned in the light path for transmitting light traveling in a predetermined scattering angle range and blocking transmission of light scattered outside said scattering angle range;   a detector positioned in the light path after the discriminating device for detecting light transmitted through the discriminating device and producing an output signal proportional to the amount of light transmitted; and   a control circuit connected to the detector output for generating an alarm output signal if the detector output is above a predetermined level.   
     
     
       2. The apparatus as claimed in claim 1, including an alarm indicating device connected to said control circuit and responsive to said alarm output signal and having an alarm condition indicator which is actuated by said alarm output signal. 
     
     
       3. The apparatus as claimed in claim 2, wherein said alarm indicating device is a light emitting diode. 
     
     
       4. The apparatus as claimed in claim 1, including a HEPA filter connected to said control circuit and having a switch for switching on the HEPA filter in response to said alarm output signal. 
     
     
       5. The apparatus as claimed in claim 1, wherein said discriminating device comprises a lens and a pinhole device positioned in series in the light path, the pinhole device having a pinhole at a predetermined position for transmitting light traveling in a predetermined angular path after the lens. 
     
     
       6. The apparatus as claimed in claim 5, wherein the pinhole is positioned for transmitting light scattered by particles in a 5 to 50 micron size range. 
     
     
       7. The apparatus as claimed in claim 1, including first and second mirrors in the light path between the blocking device and the discriminating device for reflecting light traveling on the light path through 180°. 
     
     
       8. The apparatus as claimed in claim 1, including a transparent plastic tube removably mounted in the passageway, the tube having opposite, open ends for air flow through the tube. 
     
     
       9. The apparatus as claimed in claim 8, including a grating mounted over each open end of the tube. 
     
     
       10. The apparatus as claimed in claim 1, wherein the light source is a laser diode. 
     
     
       11. The apparatus as claimed in claim 10, including a timing circuit connected to the laser diode to control the diode to pulse on and off at predetermined time intervals. 
     
     
       12. The apparatus as claimed in claim 1, including an adjustment device for adjusting said predetermined level. 
     
     
       13. The apparatus as claimed in claim 12, wherein the adjustment device comprises a variable resistor. 
     
     
       14. The apparatus as claimed in claim 12, wherein the adjustment device includes a digital counter to record the number of occurrences of allergen detection in a given duration of time. 
     
     
       15. A method of detecting the quantity of allergen particles in the air, comprising the steps of: directing environmental air to flow along a passageway;   directing a light beam from one side of the passageway transversely through the air flowing along the passageway, whereby a portion of the light beam will be scattered by any particles present in the path of the light beam;   blocking the direct light beam on the opposite side of the passageway and transmitting any scattered portion of the light beam along a light path;   blocking scattered portions of the light beam traveling in directions outside a predetermined angular range corresponding to a predetermined particle size range with a discriminating device in the light path and transmitting any part of the scattered light beam travelling within said predetermined angular range;   detecting the amount of light transmitted through the discriminating device; and   producing an output alarm signal if the amount of light detected is above a predetermined level.   
     
     
       16. The method as claimed in claim 15, wherein the step of blocking scattered portions of the light beam outside the predetermined angular range comprises placing a light blocking plate in the light path with a pinhole at a predetermined position for transmitting light traveling in the predetermined angular range. 
     
     
       17. The method as claimed in claim 16, wherein the predetermined angular range is 30° to 40°. 
     
     
       18. The method as claimed in claim 15, including the step of using the output alarm signal to activate an allergen filtering device. 
     
     
       19. The method as claimed in claim 18, including the step of switching off the allergen filtering device when the light detected falls below the predetermined level.